FR2524654A1 - OPTICAL FIBER CONNECTION DEVICE AND METHOD OF IMPLEMENTING SAME - Google Patents

Abstract

THE CONNECTION DEVICE ACCORDING TO THE INVENTION INCLUDES A REFERENCE SURFACE 1 FOR EXAMPLE A V INTENDED TO PROVIDE BUT-TO-END AT LEAST ONE PAIR OF OPTICAL FIBERS, AN ELASTIC FLANGE 4 AND POSSIBLE A FLAT FLANGE 3. THE ELASTIC FLANGE 4 INCLUDES , IN ONE EMBODIMENT, A CENTRAL REGION 10 ELASTICALLY DEFORMABLE AND A PERIPHERAL REGION 8 FORMING A STOP IN 8 WHEN TIGHTENING.

Description

OPTICAL FIBER CONNECTION DEVICE

AND METHOD OF IMPLEMENTING THE SAME

  The subject of the present invention is a connection device.

fiber optics.

  High performance optical fibers (attenuation of the order of a few decibels per kilometer) are very sensitive to constraints. Thus, the attenuation produced at the level of a connection can be multiplied by a factor of up to approximately

  up to 4 due to the addition of stresses on the fibers.

  The subject of the present invention is a connection device.

  optical fibers to minimize the contribution of

  constraints on the optical fibers at the connection.

  The device according to the invention is characterized in that it comprises a reference surface intended to have end-to-end at least one pair of optical fibers and an elastic flange to hold the optical fibers in place under the action of a strength

  transverse elastic of given intensity.

  The reference surface can comprise at least one groove adapted to the shape of the fibers. Said groove can be V-shaped.

  The elastic flange may include an elastic central region.

  demonstrable and a peripheral region with

  fixing means This peripheral region can be non-deformed

  resiliently movable so as to serve as a stop when tightening the elastic flange The elastically deformable central region can

  be attached to the elastic strap.

  The elastic flange according to the invention can be a molded plastic part having in cross section the general shape of a U, the lateral branches of which meet by an elastic wall and

thin of given thickness.

  The device may include a flat flange to hold in

  places at least one optical fiber located on one side of the connection.

  The device can be made up of parts of external contour

  cylindrical laughter arranged in a housing formed in two half-shells.

  For the connection of several optic fibers

  ques, the elastic flange may have two lateral flanges interconnected at their ends and having in their central part

  and over a given length 1, an elastically deformed membrane

  table with two parallel walls extending by converging inclined walls connected to each other by a flat wall intended to bear against the optical fibers when the

device is mounted.

  The method includes a step where the ends of the optical fibers to be connected are prepared, a step where at least one first optical fiber is placed on the reference surface, a step where a second optical fiber is placed opposite each first optical fiber, optionally a step where the elastic flange is positioned without tightening so as to position the optical fibers while leaving a freedom of movement in translation at least for each second optical fiber, a step where the end of each second optical fiber is abutted against the end of each first optical fiber and a step where we tighten in position

the elastic flange.

  The invention will be better understood with the aid of the exemplary embodiments given without limitation, together with the appended figures: FIG. 1a shows an exploded view of a first embodiment of the invention, FIG. 1b represents a detail of FIG. 1 a, namely a V for positioning optical fibers, FIGS. 2 a and 2 b represent respectively in side view and in section the flanges for positioning optical fibers according to the embodiment of FIG.

2524654-

  Figure 3 shows in side view an alternative embodiment of the flange shown in Figure 2b, Figure 4 shows an exploded view another variant of the invention, Figures 5a and 5b, 6a and 6b show details and parts of the embodiment of FIG. 4, FIG. 7 represents in cross section an embodiment of the invention in the form of a connector, FIGS. 8 a to 8 d represent parts for positioning the optical fibers of the mode 7 of the embodiment of FIG. 7, FIGS. 9 a, 9 b and 10 represent a support having a plurality of V-shaped grooves intended for connection of a plurality of optical fibers, FIGS. 11a to 11c represent a flange adapted to the

  connection of a plurality of optical fibers.

  According to FIG. La, a support 1 is provided with a V 2 for position-

  fiber optics The V is the optimal shape for a reference surface In section, the fiber is kept centered by

  geometric contact with two reference points The connection

  dement is obtained through a so-called elastic flange 4 and possibly-

  a flange 3 which are intended to be screwed into

  threads 6 of the support 1 using screws 5.

  According to FIG. 1b, the positioning V 2 has an angle of 900 between its walls and it is designed so that a fiber of diameter D protrudes from it by a given height d For example, for a fiber of 125 microns thick, exceeding

  d chosen is located in a range of 20 to 40 microns.

  According to FIG. 2 a, the flange 3 is in the form of a flat plate provided with two bores 11 According to the section in FIG. 2 b, the elastic flange 4 assumes in section the general shape of a U having a branch central 7 and two lateral branches 8 bored at 9 The two branches 8 of the U join by an elastic and thin wall 10 of length L and thickness e 1 This wall is arched outwards and protrudes by a distance of flat reference surfaces formed by the ends 8 ′ of the U. The arched shape of the wall 10 makes it possible to direct the fibers to the

  bottom of the V and avoid overlapping fibers.

  We will now describe an operation for connecting two optical fibers according to this embodiment. The first operation consists in preparing one of the optical fibers. To do this, the outer protective sheath is removed over a short length. , while keeping the optical sheath The fiber thus prepared is positioned in the V marked in 2 and it is held in position by tightening the flange 3 at a level where the sheath has not been removed As the fiber is still coated with its mechanical protection sheath, for example made of epoxy or silicone, the tightening of the flange 3 does not bring any constraints at the level of the fiber proper Furthermore, the presence of the flange 3 facilitates the fitting of the connection, since it maintains in position the first fiber during the presentation of the second fiber We then prepare the end of the other fiber and we position it in the V 2 near the end of the first fiber, with c interposition of a drop of index adapter liquid The liquid

  index adapter improves the attenuation of the connection and facilitates

  lite the handling We put the elastic flange 4 without tightening The positioning of the elastic flange 4 without tightening allows to press the second fiber at the bottom of the V while leaving it a freedom of movement in translation We then put in abutment manually the end of the second fiber against the end of the first This operation is done easily and correctly thanks to the plating of the second fiber provided by the second flange The flange 4 is then tightened by screwing the screws 5 into the threads 6 La flat flange can be subsequently dismantled When the elastic flange 4 is screwed onto the support 1, the two optical fibers are held in position in the V by an elastic restoring force due to the elastic deformation of the wall 10 This force is exerted on the stripped part of the fibers,

  which must therefore correspond to the width of the elastic flange 4.

  As stress forces applied transversely to the optical fibers would be liable to produce an attenuation, the parameters which define the wall 10 are chosen in such a way that the force applied to the fibers is low enough not to produce such drawbacks. By way of example, the elastic flange 4 has been produced from an unreinforced polycarbonate (for example the MAKROLON brand from the company BAYER). It has a density of 1.2 to 1.24 and a modulus of elasticity of 22,000 kg. / cm 2 It is easily moldable and has

  good flexural strength and good dimensional stability

  In this exemplary embodiment, the length L of the wall is 7 mm, its thickness e 1 of approximately 0.35 mm, and the excess of, of the order of 0.2 mm, for an optical fiber of 125 microns in diameter exceeding 20 to 40 microns from a groove in

is 5 V shape (see figure 2 b).

  On a measurement bench, we tested 50 connections made as above from the cleavage of a fiber with a hard optical sheath of a cable and end-to-end joining of the two ends For 46 of these, the attenuation of at connection was less than 0.1 d B,

  that is to say, practically not measurable.

  Such a connection can therefore be used as a reference

  for a test bench for attenuation of connectors.

  From the above description and example, it appears that the

  force exerted on the optical fibers located in the V depends only on the geometrical characteristics of the flange, the fiber and the V. It is on the other hand independent of the clamping force Indeed, the ends 8 'of the branches 8 of the U come in abutment on the flat wall of the support 1 and any subsequent tightening of the screws 5 does not transmit to

  the wall 10 no additional compressive force.

  According to FIG. 3, the elastic flange has a central block 7 'and two lateral branches 8 bored at 9' The two branches 8 'are separated by a cavity comprising a flat central part 14 and two housings 13 intended to receive an elastic plate 10 ' who

  plays the r 8 the of the wall 10 of FIG. 2 b.

  According to Figure 4, the elastic flange is obtained from a flat flange 3 ', and a support 21 between which is disposed an elastic piece 20 The assembly is mounted by screwing in the

  threads 6 of the support 1 According to Figures Sa and 5b, which represent

  feel the elastic part 20 in top view and in side view, this comprises two flat lateral portions 24 open at 22 up to rounded 23 intended to receive the screws 5 and a central arched portion 25 which has in lateral view the shape of 'an arc of radius R The elastic piece 20 has a thickness e 2 It can be metallic and obtained by stamping a steel plate. As an example, the steel chosen is a Cu-Be alloy spring steel, the thickness e 2 is 0.2 mm, and the excess by

  compared to the lower part of the flange 21 by 0.2 mm.

  According to Figures 6a and 6b which show the flange 21 respectively in side view and from above, it takes the shape of a U whose central branch 26 is thicker than the two lateral branches 27 so as to position the elastic piece 20 The lateral branches 27 each have a bore 29 and a chamfer 28 located on the internal side of each branch 27 The purpose of this chamfer 28 is to allow the junction zone between the flat portion 24 and the arched portion 25 of the

  elastic part 20 When the assembly is assembled, the cam-

  brée 25 of the elastic part 20 exceeds by a given amount the lower part 27 'of the flange 21 The elastic force of support on the

  optical fibers is thus determined by the mechanical characteristics

  nics of the assembly as in the case of the figure In addition, the realization of the connection of the optical fibers implements the

  same steps as in the case of FIG.

  FIG. 7 represents a connection device according to the invention in the form of an optical connector. It comprises an external casing constituted by two half-shells 31 and 32 fixed together by screws not shown. The sheathed fibers are brought to the part connector active by flanges having a cylindrical part 33 ending in a diameter part

  larger 33 'which is blocked in corresponding housing

  laying half-shells 31 and 32 A support 34 and flanges 35 and 36 are trapped between the half-shells, in a cylindrical housing S The flanges 35 and 36 are made integral with the support 34

  by clips 37 The support 34 extends over the entire length of the.

  housing available between the half-shells 31 and 32.

  The flange 34 (FIG. Sa) comprises a V 65 for positioning the fibers, which is disposed on its upper face 64 The upper face 64 is bordered by two notches 62 Its central part 60 is of generally semi-circular shape, except at its part lower o it has a flat 61 in the center of which is formed a notch 61 'in the form of a V intended to receive a branch of a clip 37 The support 34 has at its ends, and possibly in the middle a cylindrical region 63 of more diameter tall which

  corresponds to the internal diameter of the cylindrical half-shell 31.

  The flange 35 (FIG. 8 b), which plays the role of the flange 3 of FIG. 1 a, has a lower planar face 52 in which is formed a groove 54 ′ whose width corresponds to that of the upper surface 64 of the support 34 , the lower surface 52 also coming into abutment in the notches 62 The central part of the flange 35 has, as for the support 34, a cylindrical contour and its upper part consists of a flat 51 provided with a notch 51 'in the form of V intended to receive a branch of a clip 37 At each of its ends, the flange 35 is provided with a cylindrical contour 53, the diameter of which is greater than that of the

  central part 50 corresponds to the internal diameter of the half

shell 32.

  According to FIG. 8 c, the elastic flange 36, which fulfills the function of the elastic flange 4 of FIG. 1 a, has a lower face constituted by a slightly arched elastic membrane (see

  the description of the elastic membrane 10 in FIG. 2 B) The

  elastic membrane 45 is bordered by two flanges 42 having a

  lower planar surface 42 'The edges 42 are spaced and dimen-

  a sioned in such a way that the lower surfaces 42 'abut at the bottom of the notches 62 of the support 34 This makes it possible to position the fibers at their connection in the V 65 without exerting on them too great constraints, as it was previously explained The central part 40 of the elastic flange 36 has a generally cylindrical contour except at its upper part, which has a flat 41 in which es't made a notch 41 'allowing to receive a branch of a clip 37 La central part 40 has at its lower part a cavity 44 which borders the elastic membrane 45 At each end of the elastic flange 36, a cylindrical contour 43 is formed, the outside diameter of which is greater than that of the central part 40,

  corresponds to the internal diameter of the half-shell 32.

  The connection of two optical fibers implements the

  same operations as in the case of the preceding embodiments

  teeth, the flanges 35 and 36 being fixed on the support 34 by means of a clip 37 shown in FIG. 8 d This has a central portion 70 curved according to a diameter corresponding to that of the central parts 40, 50 and 60 The central part 70 has on each side a bend 71 which is extended by a straight part 72 directed inwards Each straight part 72 is extended by a bend 73 and a terminal portion 74 directed outwards, the assembly 72, 73 and 74 being intended to come and stay in

  V-shaped notches 41 ', 51' and 61 '.

  Figures 9 a and 9 b respectively show a top view and in section a support element for optical fiber intended for multiple connection and comprises a block 80 of width I and length L 1 at the upper surface of which grooves are formed. 82 V-shaped bordered at each end by grooves 81 also V-shaped but of more dimension

  important in order to facilitate the presentation of optic fibers

  This support element is intended to be inserted in a

  central support shown in section in Figure 10 This includes

  carries a block 83 having a flat upper surface 84 in which is formed a groove 85 whose width I corresponds to that of the support element described above. The upper surface 84 also includes threads 84 'intended for the

  fixing of the flange (s) of the connection device.

  Figures 11a to lic show respectively in top view, in section AA and in section BB an embodiment of an elastic flange intended to be mounted on the support described in

figure 10.

  The elastic flange has two lateral flanges 90 These are interconnected at each of their ends by sections 91 of rectangular shape in which are formed bores 92 These sections 91 do not extend to the upper surface of the flanges lateral 90 in order to leave a space available for the screw heads in the bores 92 In the central part of the lateral flanges 90, and over a length I is disposed an elastically deformable membrane which extends from a flange 90 to the other This consists of two parallel walls 93 each of which extends downward the side edges 90 The vertical walls 93 are extended by converging inclined walls 94 which are connected together by a flat portion 95 This portion is arranged in such a way that it protrudes by a distance d 'from the lower plane 91' of the sections 91 In this way, when the elastic flange is mounted on the support 83, by mounting the screws in the threads 84 'through the bores 92, the planar portion 95 supports the optical fibers in the grooves 82 over the entire length 1. The connection is advantageously carried out as follows The fibers at the end of two cables to be connected are mounted in position on a lateral support (not shown) and provided with V-shaped grooves having the same spacing as those of the central support They are prepared using a tool for collective breakage of optical fibers as described in French patent application 80 16,917 filed on July 31, 1980 by

  The Applicant Each lateral support is made in such a way

  lastly that the fibers protrude after breaking a quantity î-

  determined with precision The lateral supports are then mounted on each side of the block 83 of the central support The optical fibers are then positioned opposite one another It only remains to mount the elastic flange (Figures 11a to 11c) with interposition

possible an index liquid.

  The elastic flange shown in Figures 11a to lic can be produced by molding. For example, the material is an uncharged polycarbonate (MAKROLON brand from the company BAYER). The elastic membrane has a length I equal to II mm, a thickness el constant equal to 0.3 mm, the portion 95 has a width of 1.5 mm for a spacing of 7 mm between the side walls 93, and the protrusion of is equal to 0.2 mm for optical fibers of 125 microns in diameter and 20 to 40 microns larger than the V-shaped grooves

  The invention is not limited to the explicit embodiments.

  fully described and exemplified Thus, other materials can be used

  rials for making the flanges and in particular the elastic flanges In fact, all the elastic materials having good properties

  mechanical can be used to obtain pressure forces

  comparable to those of the examples mentioned above, it suffices to adapt the dimensions of the elastic walls taking

  account for the modulus of elasticity of the material used.

he

Claims (12)

R E V E N D I C A T I 1 O N S   1 optical fiber connection device, characterized in that it includes a reference surface (1) intended to have at least one pair of optical fibers end-to-end and an elastic flange (4) to hold the fibers in place optics under the action of a transverse elastic force of given intensity. 2 Device according to claim 1, characterized in that the reference surface (1) comprises at least one groove (2) adapted to the shape of the fibers.   3 Device according to claim 2, characterized in that said groove (2) is V-shaped.   4 Device according to one of the preceding claims, charac-   characterized in that the elastic flange (4) has a central region   elastically deformable and a peripheral region (8) present both fixing means.   5 Device according to claim 4, characterized in that the peripheral region (8) is not elastically deformable so   to serve as a stop (8 ') when tightening the elastic flange (4).   6 Device according to one of claims 4 or 5, characterized   in that the elastically deformable central region (10 ', 20) is   added in the elastic strap.   7 Device according to claim 6, characterized in that the   elastic flange (4) has housings (13) receiving a plate   elastically deformable (10 ') and arranged in such a way   that it is arched outwards.   8 Device according to claim 6, characterized in that the plate (20) elastically deformable comprises two lateral portions (24) planes and a central portion (25) arched and elastically deformable, and in that the latter is mounted between   a flange (3 ') and a support (21).   9 Device according to one of the preceding claims, charac-   terized in that it has a flat flange (3) to keep in   places at least one optical fiber located on one side of the connection.   Device according to one of the preceding claims,   characterized in that it consists of parts (34, 35, 36) of cylindrical outer contour arranged in a housing formed in two half-shells (31, 32).   11 Device according to one of the preceding claims, ca-   characterized in that, for the realization of the connection of several   fiber optics, the elastic flange (4) -has two side edges-   rails (90) interconnected at their ends and comprising in their   central part and over a given length 1, an elastic membrane   only deformable comprising two parallel walls (93) extending by converging inclined walls (94) connected together by a flat wall (95) intended to come to bear against the   optical fibers when the device is mounted.   12 Optical fiber connection device, characterized in that it comprises an elastic flange (4) of molded plastic material having in cross section the general shape of a U (7, 8), the lateral branches of which join by a wall ( 10) elastic and thin of given thickness (e 1).   13 Method of connecting optical fibers using   operates a device according to the preceding claims, character-   laughed at in that it comprises the steps of preparing the ends of the optical fibers to be connected, of placing at least one first optical fiber on the reference surface, of placing a second optical fiber facing each first optical fiber, of putting   end of each second optical fiber against the end   mite of each first optical fiber, and tighten in position the elastic strap.   14 Method according to claim 13, characterized in that it comprises a step of positioning an elastic flange without tightening so as to position the optical fibers while leaving a freedom of movement in translation at least at each second optical fiber.